Impact testing machine



y 9, 1950 R. c. M KENDRY IMPACT TESTING MACHINE 2 Sheets$heet 1 FiledOct. 18, 1946 IN VEN TOR. 19/ 67/1950 6. M lt NOE) BY m Patented May 9,1950 UNITE'D ETS OFF-[CE IMPACTTESTING MKGHINE" RicharctC. McKcndrygDayton, Ohio;

Applicationflctober '18,, 19415, ,SeriaPNo; 703,979"

( Cl. fig -1%.)?

(Granted; under. the act of .Marcli 3,. 18.8.3}; as.

amended; April .30; 1928; 3'70 6;. 757) 1 :Claim.

The invention described herein maybemanurfacturedsandz used by error..the Government for governmental purposes; without. payment/tome. of.any-royalty thereoni.

This inventionrelatesito; an impact testing, ma-' chine useful. asa-Jgeneral impact tester, but more particularly adaptedrfiorrtestingthe; force of .impact of. hammers v and. similar impact. specimens,

Onerof thew-essential objects of this invention is; toprovide, animpact. testing mechanism which i's especially adapted-ion testing: theforce .of .impact of hammers or hammer :heads or. mallet-sci. similarspecimens to asoertain the wear, breakage, and distortion-causedtheretov bytimpact in order to .aid in .accuratelyestimating thevseryicelife of specimens of that type.

Another objectiof this invention :is. to provide such: a testing machinewhich is adapted and arranged so. that .one can first:- obtainthenece'ssary impact data. through directfluse and trial of. the hammer-0130131161 impact; specimen. to "be tested, and :canwthenz.reproducethatysame force of: impact.-by: proper adiustmentof. thismachine and the subsequent continued testing; of the hammer. orspecimen:thereon.

A more; particular object .o'fxthis invention :is 'to providersuch atesting machine-adapted forrtesting, hammers and similar'handle-equipped articles whereby towclosely' simulate a 'mechaniclsgrip-on the handle and to reproduce common practica1-.:conditions,,instead .of using: arbitrary test standards, in (order to tcloselyapproach a truly reliable basis fon' predicting. the service-life of anytype of hammer-tor; similar article. being tested.

Another :object of this-invention is: to provide an impact @testerofthis kind-whereby to :obtain direct readingsef theiimpactforce infootpounds or similar uni tS'Qf force, and :pre'ferably' teaccomplishthis :by including: insuch: tester :an instrument built on the'acc'elerometer :principle wherein the: internal calibration can be.readily adjusted, so as to accommodate a. considerable ge i-na weight.and-:size: of: 37136513 articlenand :of its iiorce of. impact.

finicther objectef this invention-is; toryproyide such an impact testingmachine which utilizes impact 'receivingsanvii which...itselfiszshockand. whereon; an impact indicatinginstrument is then 'adj ustably and;"resiliently mcunted and fits-calibration can lee-readily ad- J'usted.

"Ihese:v avarious "other, objects and. advan.- tages are attained withthis invention. %as. "-wi=l1 become apparentzfronr thei iolloiving?description,

2. takenv in. connectionwith. the accompanyin dravtingswherein. theinvention is shown in.its preferred ilcrm,.it..being evident that otherarrangements; and .forms of construction may be resorted-,tnin; carryingout the objects andpurposes. of this invention.

. .In..'the.drawings,:

Eigiis a perspective. view of this novel impact. testing. machine, asseen from. one side thereof..

.EigM-ZHisHa side elevational view thereof, seen item the. sideopposite, to. that ofTFig, 1.

Fig.3 isian. end-views of the. invention showing particularly theimpact. meter,

This invention useful. assa general. impact testen. but. it. is..-more.particularly adapted for testing, .theiforce of impact of hammersmallets, and other .handle-e uipped' articles used for strikingblowsItecomprises, briefly, an impact measuring. assembly it including animpact reeeiving member l.i.,..pr,eferably.in thesform of a yieldablymountedanvil, and. an impact. indicating, .member .l.2,, preferablyincluding an, outer housing l2 and a meter 13 movably .mountedtherein,.,.said member 1:2,.being. connected. with said=..member. lgl..ancllactuated thereby; and this tester further. comprises an. article.supporting assembly M. for carrying. the. test specimen or article-.55andactuating-it.during.operation; and alsosan operating mechanism foractuating. the supporting; meanswith the-.article, thismechanism.including theudrivingassembly l6. driven by a motor I? for actuatingthe. assembly I'll with itsisupported article tiaway-from, the im.pact-member I 1., therebyraisingthe.article. l5 and. .enablingittodescend onto; said impact members. This operating mechanism. preferablyincludes means it for positively retracting; said support- .means and.thereby move. the article. force.- fullyontothe impact member it. .Anelectric counter. is.- is alsaprorided; .to.-,count. the number of..impactshf. the: article. .1 5V ontheamember I l, all-said means [0:110:ta being mounted. oniasupporting; baseorbase plateFZO.

She impact measuring assembly It includes-a supporting p1ate-2l:whereon- .the anvil H is mounted by' threading-it. onea screw .22-arising fromthe plate, and. on said plate is also mounted the-mainhousing 52 ofv saidindicating member 1 -2 as by means of. bolts 2,3 Saidplate 2| is securedxupon a plate 2 t which bears on yieldableslthpiorting: means, such: asshockmounts .2 5 which resticniaplate 25,the latterplate being adjust:- =ably securedz on; the base plate-2'0,"as by m ns :e'fibars ''k bearing; on: the ends of. said plate 26 and bythe use of bolts extending through said bars and plate. This providesfor adjustment of the anvil and the meter laterally and alsolongitudinally on the base plate 20; while shims 28 are provided, whichare preferably of various thickness, adapted to be mounted under theanvil, one or more at a time whereby to vary its height. The impactindicating member I2 is preferably arranged to indicate the impactdirectly in foot pounds, and it thus comprises the meter 43' mountedfloatingly therein, as by means of floatation springs including uppersprings 32 and lower springs 33 positioned respectively between the topends and the bottom ends of the meter casin and of the main housing 12',said springs being mounted and guided by bolts 34 and 35 threaded intonuts brazed on the top and on the bottom of the meter casing andextending through clearance holes provided in the top and in the bottomof. said housing I2. 7

,For convenience, the meter l3 may comprise a casing containing thereina standard aircraft accelerometer which has a positive or clockwisescale reading to 12 gs., and the scale is converted directly to footpounds. For each foot pound impact on the anvil this accelerometerrecords g; and the accelerometer has a return button 36 for returningits index hands 31, 38, and 39 to Zero. Said indicating member l2 canherein be readily removed bodily from the impact member I! and from themachine by merely releasing the lower mounting bolts 23, while thescrews 35 pass through oversized holes 35' in plate 2|.

The shock mounts 25 may be aircraft vibration isolators of 15 poundscapacity each. These shock mounts thus partially absorb the impact ofthe article on the anvil II and transfer the effect thereof to theaccelerometer [3 through the floatation springs 32 and 33. Thecompressibility of these springs 32 and 33 is an essential factor in thecalibration of the complete impact meter assembly, and these shockmounts and springs, together also provide a means of calibrationcontrol.

The article supporting assembly l4 includes a support 4! and this isshown herein in the form of a plate including two triangular arms 42arising from the main lower part thereof which is adjustably mounted onbase 20, as by means of bolts 43 that are securable in the desiredposition in slots 44 provided in the base 20. At the upper. parts of thetwo arms 42 is movably mountedan operating member 45 for supporting andmovingthe test article into contact with the anvil H and this member 45is herein shown as a shaft which is longitudinally adjustable in anenlarged part 46 on an axle 41, this shaft 45 being held secured in saidpart by a set screw 48. The axle is rotary in said upper "shaft 45 withthe article l5 during operation.

The invention disclosed herein is illustrated as being more particularlyadapted for testing articles that are equipped with a handle, such as ahammer and the like; and the shaft 45 is therefore provided with meansfor grasping such a handle, this means being herein shown asincluding apair of yokes 5| secured to the outer end of shaft 45 and having anupper jaw -52 and a lower jaw 52 mounted therein which -1 are preferablyof rubber or other anti-slip material and are adapted to clasp firmlytherebetween the handle 53 of the article l5, and substantially in thesame way as the handle is grasped by the hand during ordinary use. Setscrews 54 extend through the yokes to force the jaws firmly onto thehandle. A counterweight 55 is adjustably mounted on shaft 45 tosubstantially balance the weight of the hammer; and a brass tip 56 ismounted detachably on the end of the shaft opposite the hammer, so as tobe replaceable in case of excessive wear.

An extension arm 51 is secured at one end onto an upstanding arm 42 ofsupport 4|. It extends substantially horizontally therefrom toward theanvil ll, and on the free end part of this arm is mounted a needle orpointer 58 which is adjustable longitudinally of said arm and is adaptedto be' used as a reference point to aid in properly positioning theanvil and other parts while being changed.

The operating assembly l6 includes a support 6| which is similar tosupport 4| and contains two arms 62 arising from its main lower partwhich is mounted adjustably on base 20, as by means of screws 63extending from said base 20 through slots 64 provided in said lowerpart. A shaft 65 is rotary in the upper part of said arms, and it has agrooved wheel 66 secured on one end which is driven through a V-shapedbelt 61 by means of a pulley 68 driven by said motor I1. Said motor ispreferably also mounted on the base 25, and it is adjustable for speed,as by operating a hand wheel 69, the speed adjustment being indicated bya scale 10 on the motor housmg.

The means provided on this-assembly 56 for operating the shaft comprisesa pair of arms 13 secured on shaft 55 and carrying at their two ends apair of rods 14 each having a roller 15 rotatively mounted thereon, andthese rollers are so positioned as to engage the end part of tip 56 onshaft 45 and swing down said shaft end by rolling downwardly along saidtip 56, while the wheel 66 with shaft and arms 13 rotate.

By rotation of wheel 66 in a clockwise direction, as viewed in Fig. 2,the tip end 56 on shaft 45 is forced downward and the opposite end ofsaid shaft with the article l5 are forced upward. When the roller 15 hasrolled down from the end of said tip 56, then the other end with article15 will be enabled to move downward to strike upon the anvil, the meansl8 being provided for positively forcing said raised end of the shaftwith the article downwardly onto the anvil. As shown herein, this meansis conveniently provided in the form of a pair of coil springs 16 whichmay be mounted in any appropriate manner, and which are shown herein aseach spring having its lower end secured by means '51 onto the support4!, and the upper end of each spring being secured to a bracket bar 18which is adjustably mounted by means 19, such as a set of apertures anda pin, on the free end of an arm 80 which has its other end secured ontosaid enlarged part 45 of axle 41. The pair of springs 16 are herewithplaced under tension by the upward movement of the hammer, and thetension of these springs can be adjusted by adjusting the two pins inthe apertures in the two bracket bars 18 and thereby adjusting the forceof impact of the hammer or article I5 upon the anvil during thedescending operation.

9 In cooperation with the counter 19, amicroswitch 8| is provided and itis connected with said counter by an electrical conductor 82, saidswitch being mounted by bracket means 83 on the base 20. A pair of pins84 on one side of wheel 66, which pins are spaced 180 apart and timedwith the actions of the two rollers 15 onto the tip 56, will operatesaid microswitch 8| just as the hammer strikes the anvil, and thus willrecord the contacts of said rollers on said tip and thereby the numberof swings of the hammer and its impacts on the anvil.

The impact anvil H absorbs the blow of the descending hammer l andthrough deflection of the shock mounts 25 transmits the effect throughthe floatation springs 32 and 33 to the accelerometer l3.

This machine is adapted for testing various types of impact specimens,and in Fig. 2 is indicated a specimen 85 including a knuckle 85 on theend of the handle 53' which clamps therein a hammerhead 81 to be tested.

In utilizing this device, the anvil should be placed so that the head orimpact part of the hammer or mallet or other article I5, that is to betested, will be exactly level on the top face of the anvil H when thescales of the impact indicating meter [3 and of the counter I9 areplaced at zero.

The average blow struck with the type of hammer or article to be testedis first determined by having a group of mechanics or hammer users, saya dozen or more, each strike several blows with a specimen of this typeof hammer on this anvil. The force of each blow is read from the impactmeter in foot pounds, and the average of all such blows is noted forthat type and make and weight of hammer.

The machine is then adjusted, by adjusting the tension of springs 16,also the length of stroke of the hammer l5 and the position of thebalance weight 55, so that said average blow so obtained is thereafterreproduced in foot pounds impact on the machine.

The handle 53 of the hammer or other article to be tested is nextclamped between the rubber surfaces of the grasping means 5|, 52, 52,54, provided on the shaft 45, the handle being engaged at the part whichis customarily grasped by the hand of the mechanic during use. Springtension and stroke adjustment should be checked for obtaining the properfoot pounds impact. The initial position of the springs I6 should besubstantially vertical, to cut down the rebound. The speed of the motorshould be properly set to eliminate any change thereof during theextended test of the particular article. The test may be prolonged aslong as desired. The descending hammer which strikes the anvil willcause the positive or clockwise hand '38 of the accelerometer to take upthe position for which the indicating assembly 12 was calibrated and themachine adjusted; while the negative hand 39 of the accelerometer,although having no bearing on the impact, will take up a position to theleft, according to the undampened vibration present in the machine. Thespeed of the motor determines the number of contacts or impacts of therollers 15 on the tip 56 and the consequent swings of shaft 45 with theresulting impacts of the hammer on the anvil, whereof 30 to impacts perminute is a reasonable range of speed, while the stroke of the shaft 45and hammer is preferably set at approximately 35. Such testing iscontinued until the resulting wear or breakage or distortion of thearticle will indicate the length of service life of the specimen whichis being tested and thereby of other specimens of that type.

I claim:

An impact testing machine for testing handleequipped articles ofdifierent handle lengths comprising a frame, a resilient base mountedfor longitudinal adjustment on the forward end of said frame, clampingmeans for fixing said base in the adjusted position, an impact receivinganvil and an impact receiving and recording instrument both mounted onsaid resilient base, a rocking beam extending longitudinally of saidframe, pivoting means adjustable longitudinally with respect to saidbeam situated intermediate the ends of said beam for rocking said beam,a pivot supporting stand longitudinally adjustable on said frame forcarrying said pivoting means, a handle clamp carried on the forward endof said beam adjustable for grasping handles of diiTerent sizes andlengths, operating means at the rearward end of said beam, saidoperating means comprising a bearing stand adjustable longitudinally onsaid frame, an operating bar extending longitudinally of said framerotatably supported midway of its ends on a transverse shaft havingbearing in said bearing stand, rollers rotatably supported at the outerends of said operating bar positioned to strike the rearward end of saidrocking beam and force it downward as the operating bar is rotated,controllable power means adapted for rotating said operating bar on itstransverse shaft, and adjustable tension spring means adapted to drawthe forward end of said rocking beam downward and the handle equippedmember onto said anvil when said rollers pass off the end of saidrocking beam.

RICHARD C. MoKEN'DRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,462,813 McAdam July 24, 19231,583,109 Banschbach May 4, 1926 1,604,141 Amsler Oct. 26, 19262,177,876 Perrey Oct. 31, 1939 2,281,324 Preston Apr. 28, 1942 2,396,620Taxwood Mar. 12, 1946 2,398,458 Zavarella Apr. 16, 1947 I FOREIGNPATENTS Number Country Date 541,728 Great Britain Jan. 13, 1941

